The three largest classes of mandibulate arthropods are
Hexapoda (class Insecta is an alternative name), the largest class
of arthropods by far, Crustacea (crabs, shrimp, lobsters etc), and
Myriapoda, centipedes and millipedes (Figure D). The other two
classes in this phylum are Symphyla and Pauropoda. Symphyla,
garden centipedes and their relations, are soft-bodied (covered
with soft chitinous exoskeleton) mandibulates with 1 pair of
antennae, 12 pairs of jointed legs with claws, and a single pair
of unjointed posterior appendages. Less familiar are members
of class Pauropoda, such as Pauropus, tiny soft mandibulates
distinguished by branched antennae. They are similar to millipedes
(Spirobolus) but with only 11 or 12 segments and 9 or 10
leg pairs.